Thermoplastic valved bags



y 1966 Q 0. D. RHODES 3,249,287

THERMOPLASTIC VALVED BAGS Filed Oct. 21, 1963 2 Sheets-Sheet 1 CHESTERD. RHODES INVENTOR.

I BY fa qw ATTORNEY.

May 3, 1966 c. D. RHODES THERMOPLASTIC VALVED BAGS 2 Sheets-Sheet 2Filed Oct. 21, 1963 C H E S T E R D. R H O D E S INVENTOR.

UM I ATTORNEY.

United States Patent 3,249,287 THERMOPLASTIC VALVED BAGS Chester D.Rhodes, Wilbraham, Mass., assignor to Monsanto Company, a corporation ofDelaware Filed Oct. 21, 1963, Ser. No. 317,505 2 Claims. (Cl. 22962.5)

The present invention relates to novel bags and to methods for preparingsame.

In my copending application Serial No. 259,708 filed February 19, 1963,a novel valve thermoplastic bag is described wherein a plurality ofvalve sleeve members are fusion sealed to a corner portion of a tubularthermoplastic bag blank. This copending application was filed as acontinuation-in-part of a now issued United States Patent No. 3,087,670which describes a thermoplastic bag having a unitary valve sleevemember. The bags described in the specification and drawings of thepatent and the copending application are non-gusseted. It has been foundthat these bags can be further improved by gusseting the bag both withrespect toopening and closing the valve as well as in palletizing orstacking of same.

Accordingly, it is a primary object of the present invention to providenovel gusseted self-closing valve bags of substantial volumetriccapacity which are fabricated from thermoplastic materials and methodsfor .preparing same.

Other objects of the present invention will in part be obvious and willin part appear hereinafter.

These and other objects are attained in a valve bag comprising, incombination, a gusseted tubular body of thermoplastic film that issealed across its top with a top corner of said tubular body beingfolded into the bag and constituting a valve flap, and one or more valvesleeve members of thermoplastic film which are sealed at one end to thevalve flap and at a lengthwise portion thereof partially across the topof the bag.

Other objects and advantages of the invention will be apparent from thefollowing detailed description when read in conjunction with theattached drawings in which: FIG.-I is an elevation of a blank from whichthe valved bag is to be prepared;

FIG. II is an elevation of a blank which has been gusseted from whichthe valved bag is to be prepared;

FIG. III is an elevation of an alternate embodiment of a blank fromwhich the valve bag is to be prepared illustrating aplurality-,of-v'alvemembers;

FIG. IV is a fragmentary front view of the sealed valve bag illustratingthe valve mouth or opening;

FIG. V is a fragmentary perspective side view of the sealed valve bagillustrated in FIG. IV with parts broken away; and

FIG. VI is a fragmentary perspective side view of an alternateembodiment of a valve bag with parts broken away illustrating atri'angularly cut valve sleeve member.

Referring to FIG. I, the numeral designates a tube of thermoplastic filmwhich has a top peripheral edge 12 and a valve sleeve member 14 in theform of a sheet or film of thermoplastic material which is ofsubtantially thinner gauge than the body of the tube 10. The valvesleeve member 14 is fusion sealed to a corner portion of the tube 10 atthe line of seal 16. This particular drawing shows the valve sleevemember 14 sealed to the inner side of the corner portion of tube 10.This corner portion of tube 10 will eventually be folded into the tubeand is destined to become the valve flap in the finished 'bag. Prior tofolding this corner in, however, the tube and valve member are gussetedas illustrated in FIG. II. For the purposes of this invention, it is notimportant whether the valve member 14 is adhered to tube 10 before thetube is gusseted or whether the tube is gusseted first before the valvesleeve is adhered or fused in place. It

3,249,287 Patented May 3, 1966 ice is, however, important that the valvesleeve member 14 be of substantially thinner gauge than the body of thetube 10 in order to obtain the desired closure effect after filling. Inaddition, it is sometimes desirable to employ more than one valve sleevemember such as illustrated in the alternate embodiment of FIG. III.Although it is highly important that substantially thinner gaugematerial be used as the valve members in all instances, the varioustypes of materials which are packaged will generally determine whetherone or more sleeve members are more desirable. With particular referenceto FIG. III where more than one valve sleeve member is employed, it isgenerally preferred to form the sleeves of unequal length with thelongest sleeve, that is the one that extends the furthest across the topwidth of the bag, being of the thinnest gauge. A more detaileddescription of the manner by which a plurality of valve sleeves areattached to a tubular bag blank may be had by reference to my copendingUnited States application S.N. 259,708 filed February 19, 1963.

Referring to FIG. II, a gusseted tube of thermoplastic material is shownhaving a valve sleeve member 14 FIG. II is folded into the bag creatinga fold line at ap proximately the dashed line 18. FIGS. IV and Villustrate the bag blank after the fold has been completed and afterfusion sealing the top of the bag along dashed line 20. As may be seenin FIGS. II and IV, the top edge 22 of the valve sleeve member which isin a generally horizontal position in FIG. II is shown in FIG. V in agenerally vertical position. It will be noted in FIG. IV that theterminal end 24 of the top seal 20 extends to the left of seal 16 whichis employed to join the valve sleeve member to the corner portion of thetube blank 10. This is done to prevent leakage and to improve thestrength and durability of the valve.

In general, the valve sleeve will be fabricated from 0.5 to 4 mils andmore preferably from 1-2 mil film which will be membrane-like in effectwhereas the body of the tube will be fabricated from 4 to 15 and morepreferably 512 mil film.

The gusseted thermoplastic valve bags of the present invention may beprepared by affixing or sealing at least one valve sleeve member to acorner portion of an openend tubular bag blank. To form the valve, thecorner portion must be folded down into the bag to-form a valve flap.The valve sleeve member may be ailixed or sealed to this corner portioneither before or after the valve flap is formed. In any event, the valvemember is afiixed to the valve flap such that the projecting edges ofthe valve sleeve member are positioned within and in juxtapositionedparallel relationship with the open edges of the end of the tubularblank. The open end is closed and sealed across its entire lengthincluding the edges of the valve sleeve member therebetween. Thepreferred sealing means are heating elements designed to fuse theplastic layers together.

The manner by which the valve bags are filled may be described withreference to FIG. IV. When the bag is filled, the contents of the bagwill press the valve sleeve member against the top seal portion of thetube to elfect a closure. This is a somewhat different closure effectthan is obtained in the non-gusseted valve sleeve bag wherein the valveis more apt to be forced laterally against one side of the bag. In thenon-gusseted bags, the effectiveness of the closure against leakage whenthe bags are laterally stacked will depend to a large extent on whetherthe valve sleeve member is forced under or over the contained materialwherein the tendency towards leakage is greatly increased. Whether thevalve sleeve member of the non-gusseted bags is forced upwardly ordownwardly by the contained material will, of course, depend on therather random manner in which the bag is handled. With the gusseted bag,however, the valve sleeve member tends to be forced against the top sealof the bag regardless of handling. In other words, when the bags arestacked on their sides in the normal manner, the contained materialtends to flow against the top seal of the bag thereby pressing the valvesleeve member against the top seal thereby effecting a tighter closure.Consequently, improved closure effects are obtained by use of thegusseted bag as opposed to the nongusseted thermoplastic bags. Inaddition, as previously indicated, the closure effects can sometimes beimproved by utilizing a plurality of valve sleeve members.

In FIG. IV, the valve sleeve is shown in a general rectangular foldedshape. However, it is possible to vary this shape by slanting the valvemember edge 22 downwardly at various angles away from the normal. Inaddition, it is sometimes desirable, as shown in FIG. VI, to slant oneof the edges of the valve sleeve membet to form a triangle with an apex26 to obtain a stronger and more uniform seal along the top of the bag.

The valved thermoplastic bags can be fabricated from such fusionscalable plastic materials as polyethylene, polystyrene, polyethyleneterephthalate, polyvinyl chloride, polyvinyl acetate, polyvinylidenechloride, polyisobutylene, polypropylene, polytetrafluoroethylene andthe like.

The preferred material of construction is polyethylene, a solid, toughpolymer of ethylene which can be manufactured in film-form inthicknesses less than one mil. It is light in weight, extremely low inwater absorption and moisture permeability and consequently is anexcellent material for packaging uses. In addition layers ofpolyethylene can be heat sealed or fused together to present a strongbond. It is also preferable to utilize the same material for theconstruction of both the bag and the various sleeve members sinceoptimum fusion of two or more layers of film can only be accomplished ifthe fusion temperatures of the various joining layers are approximatelywithin the same temperature range.

The valved bags of this invention ordinarily will have a substantialvolumetric capacity, e.g., at least 1 cubic foot, and are designedprimarily to carry from about 50 to about 100 pounds of such commonpulverulent materials such as cement, flour, fertilizer, carbon black,chemicals and granular materials such as salt, sugar and the like. Thewalls of the bag ordinarily will have a thickness of the order of 415mils, although obviously the walls may be either thinner or thicker asindicated by the use to which the bags are to be put. Ifdesired, thewalls of the bag can be fabricated from a plurality of plies of thinthermoplastic film. The valve sleeve member or members ordinarily willbe thinner than the walls of the bag. If more than one sleeve member isused, the longest sleeve member will generally be fabricated from filmwhich is about .5 to 4 mils thick depending on the strength andflexibility of the material, and in the case of polyethylene,thicknesses of 1-2 mils are generally sufficient to effect amembrane-like flexibility in the material.

The above descriptions and particularly the drawings are set forth forpurposes of illustration only. Many variations and modifications thereofwill be obvious to those skilled in the art and can be made withoutdeparting from the spirit and scope of the invention herein described.

What is claimed is:

1. A valve bag comprising, in combination, a gusseted tubular body ofthermoplastic film that is sealed across its top, a top corner of saidtubular body being folded into the bag and constituting a valve flap andat least two valve sleeve members of thermoplastic film which is sealedat one end to the valve flap and at a lengthwise portion thereofpartially across the top of the bag; the thermoplastic film of at leastone valve sleeve member being of substantially thinner gauge than thethermoplastic film of the tubular bag body and extending the furthestacross the top of the bag.

2. The valve bag according to claim 1 .wherein the tubular body and atleast one valve sleeve member are polyethylene.

References Cited by the Examiner UNITED STATES PATENTS 2,392,094 l/1946Lee 9335 2,542,170 2/1951 Weeks.

2,660,100 11/1953 Doyle 9335 2,804,257 8/ 1957 Hasler et al 22962.5

2,959,343 11/ 1960 Rosander 22962.5

3,004,698 10/1961 Ashton 22962.5

3,040,967 6/1962 Klein M 229-62.5

3,080,102 3/1963 Ottinger 22962.5

3,087,670 4/ 1963 Rhodes 22962.5

JOSEPH R. LECLAIR, Primary Examiner.

FRANKLIN T. GARRETT, Examiner.

D. M. BOCKENEK, Assistant Examiner.

1. A VALVE BAG COMPRISING, IN COMBINATION, A GUSSETED TUBULAR BODY OFTHERMOPLASTIC FILM THAT IS SEALED ACROSS ITS TOP, A TOP CORNER OF SAIDTUBULAR BODY BEING FOLDED INTO THE BAG AND CONSTITUTING A VALVE FLAP ANDAT LEAST TWO VALVE SLEEVE MEMBERS OF THERMOPLASTIC FILM WHICH IS SEALEDAT ONE END TO THE VALVE FLAP AND AT A LENGTHWISE PORTION THEREOFPARTIALLY ACROSS THE TOP OF THE BAG; THE THERMOPLASTIC FILM OF AT LEASTONE VALVE SLEEVE MEMBER BEING OF SUBSTANTIALLY THINNER GAUGE THAN THETHERMOPLASTIC FILM OF THE TUBULAR BAG BODY AND EXTENDING THE FURTHESTACROSS THE TOP OF THE BAG.